Thirst is all about helping you "drink better". When you first use it, you will be asked to log in and/or create an account. This is so you can track what you drink, etc. For example, in order to keep track of what you drink or looked at recently, so you can go back and see what it was, we need to know who you are so we can associate those items with you.
You will then be brought to a page listing Wine/Beer/Sprits... tap one. Don't worry, you can change from one to the other easily by flicking the "Home" page for each left and right.
When searching for a wine, this should be done via the "Wine" page, and same for Beer, etc. Each icon on the category home page acts only on that category (Favorites in Wine shows only your favorite wines, switch to Beer to see your favorite beers, etc.)